... places with inside and outside intercom-munication such as bank. Dual-way Window Bank Intercom System For CounterComplete dual-way intercom system ... for places with inside and outside intercom-munication such as bank, hospital, ticket office and stock company, etc. Working Voltage:DC9V ... Box:158*87*46mm;Sub-box:91*77*23mm. Window Bank Intercom RL-9908